Canning closure and method

Abstract

A one-piece reusable closure for home canning. The closure is adapted for sealing home canning containers, such as "Mason Jars." The closure has a one-piece threaded cap with a bonded annular closed-cell foam gasket at the periphery of a central cover section positioned to seal against the jar lip. The central cover portion is dished outwardly and moves to an inwardly dished configuration when a partial vacuum is developed in the container. When the closure is unscrewed, the central cover section springs with an audible click to the outwardly dished configuration. The closure incorporates a one-way pressure relief mechanism to limit the pressure in the container. The mechanism comprises a resilient sealing member overlying an orifice in the central cover section of the lid. As the container contents are heated, gas pressure in the container will increase and force the resilient sealing member from the orifice. Gases will then be vented through the orifice under the resilient sealing member. However, upon subsequent cooling of the container contents and cessation of pressure generation within the container, the closure and resilient sealing member seals the container to enable a partial vacuum to be formed and then maintained. The closure may be initially fully tightened and need not be further tightened after heating and subsequent cooling of the container to maintain the seal and partial vacuum within the container.

I claim: 
     
       1. A sealed package under vacuum comprising a container having a body portion and an upwardly-extending neck portion which terminates in an upper circumferential sealing lip and defines a mouth; helical container thread means on the outer surface of said neck portion; and a one-piece reusable closure threadedly engaging said neck portion and sealingly secured to said container; said closure comprising a central cover section having an inner surface and an outer surface and terminating outwardly in a depending peripheral skirt having a helical skirt thread means complementary to and in threaded engagement with said container thread means, a downwardly opening annular channel being defined in said central cover section adjacent said skirt, a resilient annular gasket disposed in, and bonded to, the inner surface of said annular channel and being in sealing engagement with said lip around the entire periphery of said lip, a portion of said central cover section presenting a substantially flat exterior surface defining an orifice and having a self-biased resilient member secured to said central cover section for disengageably overlying said orifice and normally sealing said orifice but venting said package when the pressure within said container exceeds atmospheric, a portion of said closure central cover section being inwardly dished and being maintained in that inwardly dished configuration when pressure within the sealed package is subatmospheric, said inwardly-dished portion being capable of springing preferentially to an outwardly dished configuration when the pressure within the sealed package is at least atmospheric. 
     
     
       2. The sealed package in accordance with claim 1 wherein said resilient member is a resilient membrane. 
     
     
       3. A sealed package in accordance with claim 2 wherein said resilient membrane is a strip of elastic material positioned over said orifice and secured to said central cover section under tension. 
     
     
       4. A sealed package in accordance with claim 1 wherein said resilient member is a glob-like mass of resilient material. 
     
     
       5. A one-piece reusable closure for a container having a body portion and an upwardly extending neck portion having helical container thread means on the outer surface thereof and terminating in an upper circumferential sealing lip which defines a mouth, said closure comprising: a central cover section having an inner surface and an outer surface and a depending peripheral skirt having helical skirt thread means for threadingly engaging the container thread of a container; an annular gasket at the periphery of said central cover section, said gasket being bonded to said central cover section for confronting the periphery of said sealing lip;   a portion of said central cover section presenting a substantially flat exterior surface defining an orifice and havng a self-biased resilient member attached to said central cover section for disengageably overlying said orifice and normally sealing said orifice but opening said orifice to limit the pressure differential across the closure when the greater pressure is on said inner surface thereby venting said container when the pressure within said container exceeds atmospheric; and a portion of said central cover section being outwardly dished, but being movable under partial vacuum drawn against its inner surface to an inwardly dished configuration and capable of generating an audible sound upon movement.   
     
     
       6. The one-piece reusable closure in accordance with claim 5 wherein said resilient member is a resilient membrane. 
     
     
       7. The one-piece reusable closure in accordance with claim 6 wherein said resilient membrane is a strip of elastic material positioned over said orifice and secured on each end to said central cover section under tension. 
     
     
       8. The one-piece reusable closure in accordance with claim 5 wherein said resilient member is a glob-like mass of resilient material. 
     
     
       9. A sealed package under vacuum comprising a container having a body portion and an upwardly-extending neck portion which terminates in an upper circumferential sealing lip and defines a mouth; helical container thread means on the outer surface of said neck portion; and a one-piece reusable closure threadedly engaging said neck portion and sealingly secured to said container; said closure comprising a central cover section having an inner surface and an outer surface and terminating outwardly in a depending peripheral skirt having a helical skirt thread means complementary to and in threaded engagement with said container thread means, a downwardly opening annular channel being defined in said central cover section adjacent said skirt, a resilient annular gasket disposed in, and bonded to, the inner surface of said annular channel and being in sealing engagement with said lip around the entire periphery of said lip, a portion of said central cover section defining an orifice and having a mass of resilient material secured to said central cover section disengageably overlying said orifice and normally sealing said orifice but venting said package when the pressure within said container exceeds atmospheric, a coating of primer on said exterior surface of said central cover section except for an immediate area around said orifice, a vent area connected with, and extending outwardly from, said immediate area, said mass of resilient material covering, and extending beyond, said immediate area and being bonded to said primer beyond the outer periphery of said immediate area, a portion of said closure central cover section being inwardly dished and being maintained in that inwardly dished configuration when pressure within said sealed package is subatmospheric, said inwardly-dished portion being capable of springing preferentially to an outwardly dished configuration when the pressure within the sealed package is at least atmospheric. 
     
     
       10. The sealed package in accordance with claim 9 wherein said immediate area is of annular configuration. 
     
     
       11. A one-piece reusable closure for a container having a body portion and an upwardly extending neck portion having helical container thread means on the outer surface thereof and terminating in an upper circumferential sealing lip which defines a mouth, said closure comprising: a central cover section having an inner surface and an outer surface and a depending peripheral skirt having helical skirt thread means for threadingly engaging the container thread of a container; an annular gasket at the periphery of said central cover section, said gasket being bonded to said central cover section for confronting the periphery of said sealing lip; a portion of said central cover section defining an orifice and having a mass of resilient material secured to said central cover section for disengageably overlying said orifice and normally sealing said orifice but opening said orifice to limit the pressure differential across the closure when the greater pressure is on said inner surface thereby venting said container when the pressure within said container exceeds atmospheric; an exterior coating of primer on said exterior surface of said central cover section except for an immediate area around said orifice, a vent area connected with, and extending outwardly from, said immediate area, said mass of resilient material covering, and extending beyond, said immediate area and being bonded to said primer beyond the outer periphery of said immediate area; and a portion of said central cover section being outwardly dished, but being movable under partial vacuum drawn against its inner surface, to an inwardly dished configuration and capable of generating an audible sound upon movement.   
     
     
       12. The one-piece reusable closure in accordance with claim 11 wherein said immediate area is of annular configuration. 
     
     
       13. A method of canning comprising the steps of: providing a container having an upper circumferential sealing lip which defines a mouth and having container thread means in the vicinity of the mouth; providing a one-piece closure comprising a flexible, outwardly-dished central cover section terminating outwardly in a depending peripheral threaded skirt for threadingly engaging said container thread means, said closure having an annular gasket bonded to said closure adjacent said skirt, said gasket comprising resilient material for sealingly engaging said lip around the periphery of the entire lip, a portion of said central cover section defining a substantially flat exterior surface defining an orifice and having a self-biased resilient member attached to said central cover section for disengageably overlying said orifice, said member being deformable away from said orifice for venting said package when the pressure within said container exceeds atmospheric and being self-biased against said orifice for normally sealing thereagainst when the pressure within said container is less than atmospheric; filling the container with a desired quantity of product to be canned; threadingly securing said one-piece closure to said container to form a seal between said gasket and said lip and to thereby seal said product within said container together with a small volume of gas; then heating said container and said product contained therein to a predetermined elevated temperature and thereby generating within the sealed container pressure sufficient to deform said resilient member and vent at least a portion of volume of gas through said orifice to the surrounding atmosphere; then cooling said container and thereby re-effecting the sealing of said orifice by said resilient member without further manipulation of said closure so as to maintain a sub-atmospheric pressure in said container.   
     
     
       14. A method in accordance with claim 13 which includes drawing said central cover portion into a downwardly dished configuration while developing a partial vacuum in said container. 
     
     
       15. A method in accordance with claim 13 in which said one-piece closure is one which has previously been used to seal a container.